PO-015 Potentiating anti-neoplastic effect of cisplatin by a protein arginine methyltransferase 5 selective inhibitor in lung adenocarcinoma cells

Abstract

IntroductionProtein arginine methyltransferase 5 (PRMT5) is an enzyme that is greatly implicated in diverse cellular processes, including transcriptional regulation, RNA metabolism, and cell-cycle regulation. It was found in previous studies to be highly expressed in cancers including lung adenocarcinoma, Hepatocellular Carcinoma (HCC), and melanoma; in amounts much more significant as compared to benign tissues; raising evidence that PRMT5 is involved in tumorigenesis. Recent studies have proven that inhibition of PRMT5 in HCC cells through the use of AMI-1, a water soluble selective protein arginine methyltransferase inhibitor significantly reduces the proliferation and migration of HCC cells. It was also found that β-catenin is a target of PRMT5, therefore inhibiting PRMT5 resulted in the silencing of β-catenin; as well as its downstream cell-cycle regulator cyclin D1. The aim of our study is to investigate the effect of PRMT5 inhibitor (AMI-1) on the proliferation, migration and survival of lung adenocarcinoma cells.Material and methodsWe compared the effect of AMI-1 on lung adenocarcinoma (A549 cell line) suppression with the standard chemotherapeutic agent, cisplatin, by measuring cell viability using MTT assay, PMRT5/β-catenin expression via Western Blotting, the extent of cell migration through wound healing assay, and survival of cancer cells by performing cell cycle progression and Annexin-V staining assays.Results and discussionsTreating the cells with a combination of 10 µM AMI-1 and IC50 of Cisplatin (23.4 µM) significantly decreased cell viability at 24 and 48 hours. Moreover, treatment with both drugs at 48 hours led to a reduction in cell migration measured by the migration rate. AMI-1 induced G2/M arrest in A549 cells at 24 hours. This effect was enhanced in the combined treatment. Furthermore, A549 cells were unable to recycle again as they arrested at G1 after 48 hours of combination treatment. There was a minor cell death induction after 48 hours of treatment with both drugs. Neither PRTM5 nor β-catenin protein levels were affected due to the treatment. However, 48 hours treatment with AMI-1 alone or in combination with Cisplatin reduced the methylation of PRTM5- downstream target, Histone 4.ConclusionInhibition of the intracellular enzyme protein arginine methyltransferase 5 by AMI-1 potentiates the anti-cancer effect to cisplatin in the lung adenocarcinoma, with a promising potential role as an adjuvant therapy in lung cancer. The?effect is likely mediated by methylation reduction of histone-4.